A photovoltaic (PV) system converts the sun's radiation into usable electricity. PV systems range from small, rooftop-mounted or building-integrated systems with capacities from a few to several tens of kilowatts, to large, utility-scale power stations of hundreds of megawatts. Some PV systems may be connected to an electrical grid to enable transmission and distribution of their generated-electricity to other participants in the utility market. On the other hand, some PV systems, such as, for example, residential or small-scale PV systems, may be off-grid or stand-alone systems.
FIG. 1 is a simplified block diagram of an exemplary PV solar system 10. As shown, a typical PV system or PV solar site, such as, for example, the PV system 10, may comprise a solar/PV array 12 and a number of Balance of System (BOS) components, three of which—a charge controller 14, a storage (battery) unit 15, and an inverter 16—are shown in FIG. 1 by way of an example. The BOS components 14-16 may balance the power-generating sub-system of the solar array 12 with the power-using side (the electrical load). For ease of illustration, the electrical load portion is shown using blocks 18 and 20 in FIG. 1, but, in certain implementations, the electrical load 18, 20 may not be considered as part of a PV solar site.
The charge controller 14 may regulate the electrical input received from the PV array 12 so as to satisfy the demand for the Direct Current (DC) load 18 and transfer any additional electricity for storage into the battery unit 15. On the other hand, when the generated electricity (by the PV array 12) is not sufficient to satisfy the requirements of the DC load 18, the charge controller may access the stored electricity from the battery unit 15 and supply it to the DC load 18. The battery or storage unit 15 may also supply electrical energy to an inverter 16, which may convert the stored electric current from DC to AC (Alternating Current) to drive the AC load 20. The DC load 18 may represent systems or devices that operate on DC current, whereas the AC load 20 may represent systems or devices that operate on AC current. Although not shown in FIG. 1, the PV site 10 also may include additional BOS components such as, for example, power-conditioning equipments, structures and racking systems for mounting various BOS components and solar arrays, electrical wiring, cabling, and interconnections, and other electrical accessories to set up a working PV site. In some implementations, the PV site 10 may also use a solar tracking system (not shown) to improve the system's overall performance.